1. FIELD OF THE INVENTION
The present invention relates to a fuel control system whereby various operating parameters of a gas turbine engine are detected and converted into electrical signals, and the signals are in turn applied to an electrical control circuit which generates a control signal corresponding to a predetermined fuel feed pattern.
2. SUMMARY OF THE INVENTION
It is the object of the present invention to meet the following requirements.
Namely, it is an object of the present invention to provide a fuel control system for a gas turbine engine, wherein a fuel control signal is generated to meet the optimum fuel feed quantity predetermined in accordance with the idling and load conditions, such as, the acceleration, deceleration and part load operations of a gas turbine engine.
It is another object of the present invention to provide a fuel control system for a gas turbine engine, wherein a control signal corresponding to the overspeed limit is generated for each of the compressor turbine and power turbine of a two-shaft gas turbine engine to separately limit its revolution speed to the maximum revolution speed, and these signals are overridden by another control signal corresponding to the load condition of the engine.
It is still another object of the present invention to provide a fuel control system for a gas turbine engine, wherein the pressure of air at the outlet of the compressor turbine of a gas turbine engine is detected by converting it by a semi-conductor pressure transducer or the like into an electrical signal which is in turn compared with a predetermined surging limit value of the outlet air pressure corresponding to the number of revolutions of the compressor turbine to generate a control signal corresponding to the surging limitation for controlling the feeding of fuel when the compressor turbine is on the point of surging, and this control signal is overridden by another control signal corresponding to the load condition of the engine.
It is still another object of the present invention to provide a fuel control system for a gas turbine, wherein the temperature of combustion gas or exhaust gas is converted by a thermocouple or the like into an electrical signal to generate a control signal corresponding to the overheat limitation for limiting the gas temperature below a temperature limit which is dependent on the heat resisting properties of the principal component parts of the engine, and this control signal is overridden by another control signal corresponding to the load condition of the engine.
It is still another object of the present invention to provide a fuel control system for a gas turbine engine, wherein a control signal corresponding to the fire limitation under deceleration operating conditions is overridden by another control signal corresponding to the load condition of the engine including the overspeed limitation, surging limitation, overheat limitation, etc., whereby to prevent the occurrence of a fire in the burner even under these limiting conditions.
In accordance with the present invention, there is thus provided a fuel control system for a gas turbine engine comprising load control signal generating means and idling control signal generating means for detecting the operating parameters of a gas turbine engine and generating respectively a load control signal corresponding to the fuel feed quantity required by the engine under load and an idling control signal corresponding to the fuel feed quantity under the idling conditions of the engine, and an upper limit selection circuit for selecting the greater one of the signals generated from the two means and generating a fuel control signal for commanding the proper fuel feed quantity, whereby the fuel supply to the gas turbine engine used as a prime mover for an automobile or the like can be controlled by means of a fuel control signal alone in all the operating ranges of the engine.
Further provided are overspeed limiting means for generating a fuel limiting control signal to separately limit the revolution speed of each of the compressor turbine and power turbine of the gas turbine engine to the maximum revolution speed to prevent overspeed of the two-shaft gas turbine engine under load conditions. Surging limiting means are also provided for comparing the outlet pressure of the compressor of the gas turbine engine with a predetermined surging limit value corresponding to the revolution speed of the compressor turbine and generating a fuel limiting control signal to thereby prevent the occurrence of surging.
Further provided are overheat limiting means for generating a fuel limiting control signal to limit the combustion temperature of the gas turbine engine below the heat resisting limit temperature to prevent the gas turbine engine from being damaged by the overheating thereof. Further provided are deceleration control means for generating a fuel feed control signal for the fire limitation corresponding to the revolution speed of the gas turbine engine under the deceleration conditions to efficiently control the fuel supply under the idling conditions. Lastly, compensation means are provided for compensating the fuel control signal in accordance with the amount of heat supplied to the inducted air by the heat exchanger to ensure a highly accurate fuel control that suits the performance of the heat exchanger.